Autonomous in-flight refueling system

ABSTRACT

An autonomous in-flight refueling hose end unit includes a first end, a second end remote from the first end, one or more adjustable control surfaces and a flight control computer. The first end is configured to be coupled to a fuel hose of a tanker aircraft. The second end is configured to be coupled to receiver aircraft. The one or more adjustable control surfaces are adapted to fly the refueling hose end unit into contact with the receiver aircraft. The flight control computer autonomously controls the control surfaces to fly the refueling hose end into contact with the receiver aircraft. In some embodiments, the control interfaces include two wings or winglets and the second end includes a detachable boom or a detachable basket.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser.No. 60/587,540 filed Jul. 12, 2004, which is hereby incorporated byreference for all purposes.

FIELD

This invention relates to a method and apparatus for refueling aircraft,and in particular for refueling aircraft during flight (in-flight).

DESCRIPTION OF RELATED ART

There are essentially two types of military in-flight refueling systems,namely: (1) the hose and drogue unit systems used by the U.S. Navy (USN)and foreign air forces; and (2) the boom and receptacle systems used bythe U.S. Air Force (USAF). The two systems are generally incompatiblewith each other, i.e., a tanker aircraft from the U.S. Navy and foreignair forces cannot be used to refuel a USAF aircraft while a USAF tankeraircraft cannot be used to refuel a USN aircraft.

At the time of the Gulf War in the early 1990's, the inability to refuelUSAF aircraft using a foreign tanker aircraft with a drogue systemseverely impacted inter-force operability. Existing drogues are usuallyfunnel-shaped devices at the end of the hose of the tanker aircraft,used as a stabilizer and receptacle for the probe of receiver aircraftduring in-flight refueling. From the early to mid 1990's, severalstudies were performed to evaluate fitting probes to USAF aircraft toovercome this problem. This proved to be very costly since there areabout 25 times more receiver aircrafts than tanker aircrafts that wouldhave to be modified.

Accordingly, it is highly desirable to provide an in-flight refuelingsystem that allows receiver aircraft to be refueled by any type oftanker aircraft.

BRIEF SUMMARY OF THE INVENTION

According to the invention, a refueling hose end unit is provided. Therefueling hose end unit includes a first end, a second end remote fromthe first end and one or more control surfaces. The first end isconfigured to be coupled to a fuel hose of a tanker aircraft. The secondend is configured to be coupled to receiver aircraft. The one or morecontrol surfaces are adapted to fly the second end of the refueling hoseend unit into contact with the receiver aircraft. In some embodiments,the control surfaces include two adjustable wings or winglets. Thesecond end includes a boom or a basket. A flight control computer isprovided for autonomously flying the refueling hose end unit intocontact with the receiver aircraft.

The refueling hose end unit of the present invention is configured toreplace existing drogues, i.e., the refueling hose end unit attaches tothe hose of a conventional hose/drum unit or pod-based hose of thetanker aircraft. This allows receiver aircraft to be refueled by a USN,foreign, or USAF tanker aircraft, without little, if any, modificationsto the receiver aircraft.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the nature and objects of the invention,reference should be made to the following detailed description, taken inconjunction with the accompanying drawing, in which:

FIG. 1 is an isometric view of a system for in-flight refueling ofreceiver aircraft, according to an embodiment of the invention;

FIG. 2 is a side view of a flying hose end unit as attached to a tankeraircraft shown in FIG. 1, according to an embodiment of the invention;and

FIG. 3 is a flow chart of a method of connecting a tanker aircraft to anin-flight receiver aircraft, according to an embodiment of theinvention.

Like reference numerals refer to the same components throughout thefigures.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is an isometric view of a system 100 for in-flight refueling ofreceiver aircraft. The system 100 includes a tanker aircraft 102 usedfor refueling receiver aircraft 104. The tanker aircraft 102 may be anysuitable tanker, as is known to those of skill in the art. The receiveraircraft may be any suitable receiver aircraft. For example, FIG. 1depicts two distinct receiver aircrafts 104(a) and 104(b). In someembodiments, the receiver aircraft 104(a) is configured to be refueledby a USN or foreign/international tanker aircraft. Such receiveraircraft includes a probe 105 for receiving a “basket” type drogue. Insome embodiments, the receiver aircraft 104(b) is configured to berefueled by a USAF tanker aircraft. Such receiver aircraft includes areceptacle 110 for receiving a boom (or hose) from the tanker aircraft.

The present invention replaces both the “basket” type drogue and boomsystems. As shown in FIG. 1, the “basket” drogue is replaced by arefueling hose end unit 108(a). The refueling hose end unit 108(a) isconfigured to be flown autonomously, i.e., with little, if any, humansupervision, into contact with the probe 105 of the receiver aircraft104(a). The autonomous flying hose end unit 108(a) incorporates one ormore control surfaces, such as two adjustable small wings or winglets109 that may be electro-mechanically operated. These winglets 109 may bedisposed at a high dihedral angle. Rotation of these winglets isperformed on an individual basis to provide both vertical and lateralflight control, i.e., pitch and roll. Additional surfaces may beprovided to control yaw, such as a rotatable vertical tail fin.Longitudinal flight control (towards or away from the tanker aircraft)is achieved by active operation of a drum unit on the tanker aircraft102, i.e., rolling and unrolling the drum unit to extend or retract theautonomous flying hose end unit 108(a) relative to the tanker aircraft102. The autonomous flying hose end unit 108(a) may also include a shortextension that extends from the tail end of the unit 108(a). Theextension ends with a basket 106 that is configured to be received by astandard fuel probe 105 on the receiver aircraft 104(a). In anotherembodiment, the flying hose end unit 108(a) has a boom-style interfaceto mate with a standard USAF receiver aircraft receptacle on receiveraircraft.

In some embodiments, the winglets and the drum-extension position of theflying hose end unit 108(a) are controlled by an autonomous flightcontrol computer 112. The autonomous flight control computer 112 may beinstalled inside the tanker aircraft 102 as shown in FIG. 1.Alternatively, the autonomous flight control computer 112 may beinstalled inside the flying hose end unit. In either case, theautonomous flight control computer 112 effectively “flies” the basket106 of the flying hose end unit 108(a) into contact with the probe 105on the receiver aircraft 104(a), thereby allowing refueling to takeplace after a predetermined level of contact is achieved.

The autonomous flight control computer 112 receives feedback informationidentifying the positions of the flying hose end unit 108(a) withrespect to the tanker aircraft 102 and/or the receiver aircraft 104(a).In one embodiment, this feedback information is from a camera and objectrecognition software mounted on the flying hose end unit 108(a). In thiscase, there is no need to modify any of the receiver aircraft.Alternatively, this feedback information is from a system that includesa signal source such as a small light-emitting diode (LED) recognitionlamp added to the receiver aircraft and a light sensor on the hose endunit 108(a). Clearly, this configuration requires at least the additionof a LED lamp to the receiver aircraft 104(a), which, in most cases, isa small and inexpensive modification.

Note that whenever it is required to refuel navy or foreign aircraft,the flying hose end unit 108(a) can be replaced by a traditional“basket” drogue using a quick-disconnect type interfacing attachment.

Similarly, for receptacle-style receiver aircraft such as those used bythe USAF, an autonomous flying hose end unit 108(b) is provided. Theautonomous flying hose end unit 108(b) is very similar to the autonomousflying hose end unit 108(a) except that it includes a short boom 111that extends from the tail end thereof instead of an extension and abasket. The short boom 111 is configured to be received within astandard fuel receptacle 110 on receiver aircraft 104(b).

FIG. 2 is a side view of the flying hose end unit 108(a) or 108(b) asattached to tanker aircraft 102 shown in FIG. 1. One or more under-wingrefueling pods 202 are attached to the underside of one or both wings204 of the tanker aircraft 102. Each pod 202 is attached to a wing 204via a wing pylon 206. The autonomous flying hose end unit 108(a) or108(b) is attached to the pod 202 via a retractable hose 208 that can beunreeled. The flying hose end unit 108(a) or 108(b) can be configured toserve USAF aircraft with a boom and a receptacle, or USN or foreignaircraft with a probe and a drogue. The flying hose end unit 108(a) or108(b) may include a receiver connection 210 for removeably attaching abasket 106 or a short boom 111 to the flying hose end unit 108(a) or108(b). In some embodiments, a ram-air turbine 212 is provided togenerate power. For example, the turbine 212 may be used to power thedrum that unreels the hose 208 and the flying hose end unit 108(a) or108(b).

201 FIG. 3 is a flow chart of a method of connecting a tanker aircraftto an in-flight receiver aircraft. First, an appropriate detachableinterface device is selected in accordance with the receiver aircraft(310). In some embodiments, the detachable interface device is adetachable boom for USAF receiver aircraft or the like. This detachableboom is specially designed to mate with a standard receptacle on thereceiver aircraft. In some other embodiments, the detachable interfacedevice is a detachable basket for receiver aircraft associated with theU.S. Navy or foreign air forces. This detachable basket is speciallydesigned to receive a standard fuel probe on the receiver aircraft.

Next, the detachable boom or basket is attached to the flying hose endunit of tanker aircraft (320). The flying hose end unit is coupled tothe tanker aircraft via a retractable hose.

In some embodiments, an instrument such as a camera or a light sensor ispre-installed on the flying hose end unit. This instrument is used fordetermining a current position of the receiver aircraft with respect tothe refueling hose end unit (330). For example, the camera first takes apicture of the receiver aircraft. The image of the receiver aircraft istransmitted to a flight control computer in the tanker aircraft througha wired or wireless communication channel. Object recognition softwarerunning in the computer processes the image to identify the receiveraircraft in the image and determine its current position based on thesize and orientation of the receiver aircraft in the image. Afterdetermining the receiver aircraft's current position, the flight controlcomputer generates instructions in accordance with the current position.These instructions are used against the control surfaces by, e.g.,adjusting the winglets of the flying hose end unit and to autonomouslyfly the hose end unit into contact with the receiver aircraft (340).

At a predetermined time interval, a new picture is taken of the receiveraircraft. The flight control computer processes this new image to checkif the flying hose end unit is closer to the receiver aircraft, and thenupdates the current position of the receiver aircraft. The flightcontrol computer uses this updated position to generate new instructionsfor the flying hose end unit until the flying hose end unit, or morespecifically the detachable boom or basket, is in physical contact withthe receiver aircraft (350, Yes). If not (350, No), this process isrepeated until the condition is met and the end unit contacts thereceiver aircraft.

Note that the whole process may be controlled by a specially designedsoftware system running in the flight control computer. Under theguidance of the software system, the flying hose end unit fliesautonomously towards the receiver aircraft without human intervention.In some embodiments, while the flying hose end unit actively approachesthe receiver aircraft, the receiver aircraft may also actively approachthe flying hose end unit.

The foregoing descriptions of specific embodiments of the presentinvention are presented for purposes of illustration and description.They are not intended to be exhaustive or to limit the invention to theprecise forms disclosed. Obviously many modifications and variations arepossible in view of the above teachings. The embodiments were chosen anddescribed above in order to best explain the principles of the inventionand its practical applications, to thereby enable others skilled in theart to best utilize the invention and various embodiments with variousmodifications as are suited to the particular use contemplated. It isintended that the scope of the invention be defined by the followingclaims and their equivalents.

1. A refueling hose end unit, comprising: a first end configured to becoupled to a fuel hose of a tanker aircraft; a second end configured tobe coupled to a receiver aircraft; one or more adjustable controlsurfaces configured to fly said refueling hose end unit into contactwith said receiver aircraft; and a flight control computer configured tocontrol said control surfaces to fly said refueling hose end unit intocontact with said receiver aircraft.
 2. The refueling hose end unit ofclaim 1, wherein said control surfaces include two winglets coupled tosaid refueling hose end unit between said first and second end.
 3. Therefueling hose end unit of claim 2, wherein the two winglets have apredetermined dihedral angle.
 4. The refueling hose end unit of claim 2,wherein a first of said two winglets is adapted by said flight controlcomputer independently from a second of said two winglets.
 5. Therefueling hose end unit of claim 1, further comprising a detachable boomcoupled to said refueling hose end unit near said second end.
 6. Therefueling hose end unit of claim 5, wherein said detachable boom isconfigured to be received by a standard fuel receptacle on the receiveraircraft.
 7. The refueling hose end unit of claim 1, further comprisinga detachable basket coupled to said refueling hose end unit near saidsecond end.
 8. The refueling hose end unit of claim 7, wherein saiddetachable basket is configured to be received by a standard fuel probeon the receiver aircraft.
 9. The refueling hose end unit of claim 1,further comprising: a camera mounted on said refueling hose end unit,said camera configured to provide information for said flight controlcomputer to determine a position of said refueling hose end unit withrespect to said receiver aircraft.
 10. The refueling hose end unit ofclaim 1, further comprising: a light sensor mounted on said refuelinghose end unit, said light sensor configured to provide information abouta signal source on said receiver aircraft for said flight controlcomputer to determine a position of said refueling hose end unit withrespect to said receiver aircraft.
 11. The refueling hose end unit ofclaim 1, wherein said flight control computer autonomously flies saidrefueling hose end unit into contact with the receiver aircraft.
 12. Amethod of connecting a tanker aircraft to an in-flight receiveraircraft, comprising: selecting an appropriate detachable interfacedevice in accordance with the receiver aircraft; attaching thedetachable interface device to a refueling hose end unit of the tankeraircraft; determining a current position of the receiver aircraft withrespect to the refueling hose end unit; flying said refueling hose endunit towards said receiver aircraft based on said current position; andrepeating said determining and flying steps until said refueling hoseend unit is in physical contact with said receiver aircraft.
 13. Themethod of claim 12, further comprising adjusting at least one controlsurface on said refueling hose end unit based on said current position.14. The method of claim 12, further comprising: selecting a detachableboom in accordance with the receiver aircraft; and flying saiddetachable boom into contact with a standard fuel receptacle on thereceiver aircraft.
 15. The method of claim 12, further comprising:selecting a detachable basket in accordance with the receiver aircraft;and flying said detachable basket into contact with a standard fuelprobe on the receiver aircraft.
 16. The method of claim 12, furthercomprising: capturing a signal generated by a signal source on thereceiver aircraft; and determining the current position of the receiveraircraft with respect to said refueling hose end unit based on thesignal.
 17. The method of claim 12, wherein said refueling hose end unitis autonomously flown towards said receiver aircraft by a flight controlcomputer.
 18. A tanker aircraft, comprising: at least one refueling podattached to a tanker aircraft; at least one refueling hose end unitcoupled to said at least one refueling pod via a retractable hose, saidrefueling hose end unit including; a first end configured to be coupledto the retractable hose; a second end configured to be coupled to areceiver aircraft; one or more adjustable control surfaces configured tofly said refueling hose end unit into contact with said receiveraircraft; and a flight control computer configured to control saidcontrol surfaces to fly said refueling hose end unit into contact withsaid receiver aircraft.
 19. The tanker aircraft of claim 18, whereinsaid control surfaces include two winglets coupled to said refuelinghose end unit between said first and second end.
 20. The tanker aircraftof claim 19, wherein the two winglets have a predetermined dihedralangle.
 21. The tanker aircraft of claim 19, wherein a first of said twowinglets is adapted by said flight control computer independently from asecond of said two winglets.
 22. The tanker aircraft of claim 18,wherein said second end includes a boom detachably coupled to saidrefueling hose end unit near said second end.
 23. The tanker aircraft ofclaim 22, wherein said boom is configured to be received by a standardfuel receptacle on the receiver aircraft.
 24. The tanker aircraft ofclaim 18, wherein said second end includes a basket detachably coupledto said refueling hose end unit near said second end.
 25. The tankeraircraft of claim 24, wherein said basket is configured to be receivedby a standard fuel probe on the receiver aircraft.
 26. The tankeraircraft of claim 18, wherein said flight control computer autonomouslyflies said refueling hose end unit into contact with the receiveraircraft.
 27. The tanker aircraft of claim 18, further comprising: acamera mounted on said refueling hose end unit, said camera configuredto provide information for said flight control computer to determine aposition of said refueling hose end unit with respect to said receiveraircraft.
 28. The tanker aircraft of claim 18, further comprising: alight sensor mounted on said refueling hose end unit, said light sensorconfigured to provide information about a signal source on said receiveraircraft for said flight control computer to determine a position ofsaid refueling hose end unit with respect to said receiver aircraft. 29.The tanker aircraft of claim 18, wherein said flight control computer isconfigured to control the retractable hose using a ram-air turbine. 30.A refueling hose end unit, comprising: a first end configured to becoupled to a fuel hose of a tanker aircraft; a second end configured tobe coupled to a receiver aircraft via a detachable interface device; andone or more adjustable control surfaces configured to fly said refuelinghose end unit into contact with said receiver aircraft.
 31. Therefueling hose end unit of claim 30, wherein said control surfacesinclude two winglets coupled to said refueling hose end unit betweensaid first and second end.
 32. The refueling hose end unit of claim 31,wherein the two winglets have a predetermined dihedral angle.
 33. Therefueling hose end unit of claim 30, wherein said detachable interfacedevice is a detachable boom configured to be received by a standard fuelreceptacle on the receiver aircraft.
 34. The refueling hose end unit ofclaim 30, wherein said detachable interface device is a detachablebasket configured to be received by a standard fuel probe on thereceiver aircraft.
 35. The refueling hose end unit of claim 30, furthercomprising: a flight control computer configured to control said controlsurfaces to autonomously fly said refueling hose end unit into contactwith said receiver aircraft.
 36. A refueling hose end unit, comprising:a first end configured to be coupled to a fuel hose of a tankeraircraft; a second end configured to be coupled to a receiver aircraftvia one of a detachable boom and a detachable basket; and one or moreadjustable control surfaces configured to fly said refueling hose endunit into contact with a receiver aircraft.
 37. The refueling hose endunit of claim 36, wherein said control surfaces include two wingletscoupled to said refueling hose end unit between said first and secondend.
 38. The refueling hose end unit of claim 37, wherein the twowinglets have a predetermined dihedral angle.
 39. The refueling hose endunit of claim 36, further comprising: a flight control computerconfigured to control said control surfaces to autonomously fly saidrefueling hose end unit into contact with said receiver aircraft.